You can use IEBGENER to produce a reblocked output data set containing either fixed-length or variable-length records having a logical record length that differs from the input logical record length.

When you create a data set with a logical record length that differs from that of the input data set, you must specify where each byte in the output records is to come (either from literals or from input records). Any unspecified fields will contain unpredictable data. You cannot alter the logical record length if both the input and output data sets have variable or variable blocked record formats and the output record length is smaller than the input record length.